Only render particles on silhouette of model
Cycles Render with Particles



In the above image are numerous undesirable issues.  Some might disappear with a little thought.  Convex sphere works easily.  Concave Box with visible inside and outside is more difficult. The simple cube can have difficult glancing angles.  Surface Normal testing is not enough in the general case.  Material Nodes.

Alternatives





Compositing.  Alpha Over Node. Transparent Background. Optional Render with Emission BSDF glowing particles. Composite Blur Node - Gaussian. Blurr bright glow colors. Dilate Node to increase blur size.  Multiple layers composited if particles are used in final composition. Object ID or Material ID can be use to select desired pixels in the compositor.  Stylized Blur.
Freestyle and Compositing.







Volume Shading with Emission




Below image.  Quickly contrived Volume Shading.  Meshes that Shrink/Fatten in a visually acceptable manner make this possible. Convex, Sphere, Torus Meshes.